- Agree to avoid trying to become pregnant or causing someone to become pregnant. Agree not to donate sperm or participate in other fertilization procedures. If participating in sexual activity that could lead to pregnancy, the study volunteer and/or partner must use 2 reliable methods of birth control at the same time, while taking study drugs, and for 6 weeks after stopping the drugs. Male volunteers are allowed to be sexually active without the use of birth control if they have had a successful vasectomy or are sterile.